Single pole, double throw centrif-ugally operated mercury switch



Dec. 12, 1961 H. E. RUEHLEMANN 3,012,504

SINGLE POLE, DOUBLE THROW CENTRIFUGALLY OPERATED MERCURY SWITCH Filed OCT. 15, 1954 FIG.3.

FIG.1.

INVENTOR H. E. RUEHLEMANN United States Patent Office 3,912,564 Patented Dec. 12, 1961 3,012,504 SlNGLE PQLE, DOUBLE THROW CENTRKF- UGALLY OPERATED MERCURY SWITCH Herbert E. Ruehlemann, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Oct. 15, 1954, Ser. No. 463,079 Claims. (Cl. 102-701) (Granted under Title 35, UJS. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a mercury switch and more particularly to a centrifugally actuated time delay mercury switch suitable for use with a continuously rotating member such, for example, as an electrical fuzed projectile. I

Moreover, the invention provides a new and improved mercury switch constructed and arranged to normally short an electroresponsive detonator such, for example, as the type used in electrical and radio fuzes and which will not be unshorted in response to a sudden shock.

Heretofore switches of this type have not proven entirely satisfactory particularly when used in electric fuzed projectiles for the reason that they operate falsely in response to sudden shocks during handling and transportation. They also lack the desired characteristics possessed by the device of the instant invention of operating at both high and low projectile spin such, for example, as when the projectile is propelled from the gun in response to either a full propellent charge or a half or greatly reduced propellent charge. Furthermore, such switches lack the desired delay characteristics and thus the projectile would arm and fire prematurely.

The present invention contemplates the provision of a new and improved mercury switch which overcomes the aforesaid disadvantages encountered in prior art devices by providing a slow acting switch sufi'iciently rugged to withstand sudden and severe shocks without damage or actuation thereof and which operates satisfactorily by centrifugal force in a projectile propelled from a gun at either a high or low rate of speed.

An object of the present invention is to provide a new and improved centrifugally actuated mercury switch suitable for use in an electric fuze which is characterized by satisfactory timing relative to spin performance.

Another object of the invention is the provision of a centrifugally actuated mercury switch which is responsive to either a low or high rate of spin.

A further object is the provision of a normally shorted centrifugal switch suitable for use in an electric fuzed projectile for arming an electroresponsive detonator in predetermined time delayed relation with respect to the firing of the projectile from the gun.

Still another object of the invention is the provision of a single pole double throw mercury switch for use in a projectile fuze circuit for normally shorting an electroresponsive detonator and for unsh'orting and connecting the detonator in series with a source of electrical energy when the projectile has been fired from a gun and traveled a predetermined distance from the muzzle thereof.

A still further object of the invention is the pro-vision of a new and improved mercury switch for use in an electric fuzed projectile wherein means are provided for preventing premature arming of the fuze.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary elevational view of a projectile partially broken away illustrating the manner in which the circuit controlling and delay mercury switch may be mounted therein;

FIG. 2 is an enlarged longitudinal sectional view of the switch constructed in accordance with the present invention;

FIG. 3 is a circuit arrangement suitable for use with the present invention.

Referring now to the drawing and more particularly to FIG. 1 thereof the numeral 19 generally indicates a spin projectile comprising a shell 11 having a conventional electric nose fuze 12 secured thereto. The switch of the present invention is generally indicated by the reference a character 13, the switch being mounted in the projectile in such a manner as to be readily operated in response to the spin of the projectile along its trajectory after the projectile has been fired from a gun.

, As more clearly shown on FIG. 2 the switch 13 comprises an elongated cylindrical casing 14 composed of suitable electrical conducting material such, for example, as stainless steel or the like. The casing 14 is sealed at one end thereof by a plug or bead 15, the plug being disposed between an internal flange 16 and an external flange 17 formed on the outer end of the casing 14, the other end of the casing being sealed by a plug 18 disposed between an internal flange 1 and an external flange 21 formed on the other end of the casing. Disposed midway between the aforesaid elements 15 and 18 is a delay unit generally indicated by the reference character 22. By the aforesaid arrangement a pair of chambers 2324 are formed within the casing 1 4, chamber 23 having a quantity of mercury 20 disposed therein preferably sufi'icient to substantially fill the chamber;

The delay unit 22 is disposed between a pair of mutually spaced flanges 25 formed on the casing 14, the flanges and delay unit being welded as at 26 to provide an annular head or sealing joint therebetween. Thus by this arrangement and the sealing plugs 15-18 the mercury 20 is hermetically sealed within the casing 14.

The delay unit 22 comprises a disc 27 composed of any material suitable for the purpose such, for example, as stainless steel or the like and having a centrally disposed crown portion 28 provided with a centrally arranged aperture 29, the aperture being substantially .0055 of an inch in diameter. The delay unit includes a porous sintered disc or diaphragm 31 composed preferably of stainless steel, the disc having an outer portion 32 of less density and greater porosity than the central portion 33 thereof. By the aforesaid disc arrangement a relatively shallow cavity 34 is provided between the discs.

The minute opening 29 on the disc 27 functions to meter the flow of mercury from chamber 23 into cavity 34 when the switch is subjected to centrifugal force and thence the mercury is forced through the porous portion 32 of the disc 31 in response to the aforesaid force. The sintered disc 31, however, functions to prevent flow of mercury into the chamber 24 in response to sudden and severe shock. Moreover, the cavity 34 between discs 2731 functions to receive the mercury forced through aperture 29 in response to the aforesaid shock, the mercury being maintained therein for the duration of the shock by reason of the centrally disposed dense portion 33. When the shock wave has subsided, surface tension of the mercury in cavity 28 causes the mercury within the cavity to be drawn back, into chamber 23 thereby restoring the switch to the initial condition. By the aforesaid disc arrangement it .will be apparent that the mercury will not flow through disc 31 in response to sudden and severe shock. The mercury, however, will readily flow through the disc 31 when the device is subjected to a continued application of centrifugal force.

As more clearly shown on FIG. 2 an electrode 35 is ;ealed with the bead 15, one end of the electrode being iisposed within the mercury and the other end thereof :xtending beyond the outer surface of the plug 15, thereby provide means for establishing an external electrical :onnection thereto, the electrode 35 being normally ihorted to the casing 14 by the mercury. The plug 18 is provided with an electrode 36 sealed therein and having me end thereof disposed within chamber 24 and the )ther end thereof extending beyond the outer surface of :he plug 18 thereby to provide means for establishing an :xternal electrical connection thereto.

Referring now to the circuit arrangement of FIG. 3 for t more complete understanding of the operation of the lWltCh it will be noted that the circuit includes an electro- 'esponsive detonator 37 and a conventional inertia actult6d generator 38. The detonator is connected to the :onductive casing 14 by conductor 39, and to the electrode 55 by conductor 41, the generator being connected to the :lectrode 36 by conductor 42 and to one terminal of the letonator by conductor 41. By this arrangement the letonator is normally shorted and will remain shorted mtil the mercury is moved from chamber 23 into chamier 24 by centrifugal force and the firing circuit is normally open. As the projectile is fired from a gun and .pins along its trajectory centrifugal force causes the merzury to flow from chamber 23 into chamber 24. Thus it vill be apparent that when suflicient mercury flows from :hamber 23 into chamber 24 the detonator is unshorted 1nd the normally open firing circuit is closed from the generator to the detonator by way of conductor 42, elec- .rode 36, mercury casing 14, conductor 39 connected to ,he casing and to one terminal of the detonator and coniuctor 41 connected to the generator and to the other :erminal of the detonator. Thus upon impact of the arojectile with a target the generator is operated in re- ;ponse to an inertial force and generates an electrical impulse of sufiicient strength to fire the detonator.

Although the switch has been shown and described in :onnection with a firing circuit for initially shorting the :lectroresponsive detonator included therein it will be mderstood that the switch may be advantageously emaloyed for initially shorting the generator or any other electrical power source whereupon the power source is naintained ineffective to fire the detonator until the switch s actuated to cause unshorting of the power source and :0 connect the detonator thereto.

From the foregoing it will be understood that a new and improved mercury switch has been devised for use In an electric fuze circuit for normally shorting the eleczroresponsive detonator included therein and for unshort- .ng and connecting the detonator in series with a source 9f electrical energy when the projectile has been fired from a gun and traveled a predetermined distance from :he muzzle thereof. Moreover, the aforesaid switch is :onstructed and arranged to operate in response to either a low or high rate of spin of the projectile and will withstand repeated shock without operation of the switching elements.

Although the present invention has been described in connection with a spin projectile, it will be understood that if desired the switch may be employed for delaying the operation of numerous electrical devices and elements.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A spin actuatable mercury switch for arming an electric fuze of a projectile and comprising an elongated electrical conducting envelope, means including a porous diaphragm arranged transversely within said envelope and carried thereby forming two chambers, a pair of electrodes, each of said electrodes being disposed within one of said chambers respectively adjacent but not in contact with said diaphragm, a copious quantity of mercury arranged within one of said chambers sufficient to establish an electrical connection between the respective electrode and the envelope, said porous diaphragm retarding the flow of mercury therethrough in response to a sustained force applied thereto by the spin of the projectile thereby to provide a predetermined delay in switching the electrical connection to the envelope from the first electrode to the other electrode, an electrical circuit connected to the other electrode and said envelope and rendered effective when said electrical connection to the envelope is switched from the first electrode to said other electrode, and impulse responsive firing means included in said circuit and operated as the projectile strikes a target.

2. A spin operated mercury switch for a projectile comprising an elongated electrical conducting envelope for mounting within the projectile transverse to the axis thereof, a delay element including a porous bai'lle member arranged transversely within said envelope forming two chambers, a pair of electrodes, each of said electrodes being disposed within one of said chambers respectively, a quantity of mercury disposed within one of said chambers normally shorting the first of said electrodes to said envelope, an electroresponsive detonator connected to the envelope and said first electrode and normally shorted thereby, and a normally open firing circuit connected to the second electrode and to the detonator, said firing circuit being closed in predetermined time delay relation as the mercury is forced through the porous baflle member from said one chamber to the other chamber by the spin of the projectile during flight.

3. A spin actuatable mercury switch for arming an electrical fuze of a spin projectile and comprising an elongated electrical conducting casing, a diaphragm sealed transversely within said casing forming two chambers, a pair of electrodes disposed within said chambers respectively, a quantity of mercury disposed within one of said chambers for establishing an initial electrical connection between one of said electrodes and the casing, said mercury interrupting said electrical connection between the casing and said one electrode and establishing an electrical connection between the other electrode and the casing as the mercury is switched from said one chamber to the other chamber in response to a sustained force applied thereto by the spin of the projectile, a porous section within said diaphragm for delaying the switching of said mercury, an electrical circuit connected to the other electrode and said casing and rendered elfective as said mercury is switched from said one chamber to the other chamber and the electrical connection is established between said other electrode and the casing, and impact responsive firing means included in said circuit and operated as the projectile strikes a target.

4. A spin actuatable mercury switch for arming an electric fuze of a projectile and comprising an elongated electrical conducting casing, a porous diaphragm arranged transversely within said casing thereby to provide two chambers, a pair of electrodes disposed within said chambers respectively and insulated therefrom, a pair of mutually spaced insulating members arranged within said casing for respectively supporting and insulating said electrodes from said casing, a quantity of mercury arranged within one of said chambers sufficient to establish an electrical connection between the respective electrode and the casing, said diaphragm retarding the flow of the mercury therethrongh in response to a sustained force. applied thereto by the spin of the projectile for switching the electrical connection to the casing from the first electrode to the other electrode when a predetermined period of time has elapsed, an electrical circuit connected to the other electrode and said casing and rendered effective when the electrical connection to the casing is switched from said first electrode to said other electrode,

5 and impact responsive firing means included in said circuit and operated as the projectile strikes a target.

5. A spin operated mercury switch for a projectile comprising a sealed elongated conducting casing for mounting within the projectile transverse to the axis thereof, a porous delay unit arranged transversely within said casing forming two chambers, a pair of electrodes disposed within said chambers respectively, means sealed Within each of said chambers for supporting and insulating said electrodes from the casing, a quantity of mercury disposed within one of said chambers normally connecting one of said electrodes electrically to the easing, an electroresponsive detonator connected to said one electrode and the casing and normally shorted thereby, a firing circuit connected to the other electrode for connection to the detonator in predetermined time delay relation as the mercury is forced through said porous delay unit from said one chamber to the other chamber by the spin of the projectile along its trajectory and an impact responsive generator included in said firing circuit for firing said detonator as the projectile strikes'a target.

2,414,836. Rickmeyer Ian. 28, 1947 

